The present invention relates to improvements in electromagnetic rotation detecting apparatus and more particularly to the reduction of the size of a rotation detecting apparatus of the magnetic detection type in which at least one pulse in each of two or more different series of signals is generated for every rotation of the apparatus. That is, a first signal is generated by an electromagnetic coil type pickup and a second signal is generated by a magnetoresistance effect element or Hall generator.
FIG. 1 shows an example of the above-mentioned rotation detecting apparatus for generating two or more series of signals, in which electromagnetic coil type pickups 4 and 14 are respectively arranged to face signal rotors 3 and 13 which are mounted on a rotary shaft 1 with a spacing S there between. With this known construction, it is necessary to suitably provide the spacing S such that, as for example, a leakage flux generated from the permanent magnet of one of the electromagnetic coil-type pickups as shown at numeral 19 in the Figure is not easily detected by the other electromagnetic coil type pickup, and this makes it difficult to reduce the size of the apparatus.